The present invention relates to an improvement in a remote-controlled pressure regulator which is used, for example, in automatically controlling the pressure of treating gas used in the production of semiconductors or the like.
The pressure regulators heretofore used for controlling the pressure of noxious or explosive gas are of the manual adjustment type with an ordinary manipulating or adjusting knob, even when the pressure regulator is performed automatically. These conventional pressure regulators are unsatisfactory in terms of safety so that demand has arisen for pressure regulators which can be controlled not by hand but remotely be means of an electric motor or the like, and such remote-controlled pressure regulators have come into use.
In the existing remote-controlled pressure regulators, however, the control shaft of a pressure-regulating unit and the output shaft of the drive motor are coupled to each other by means of a spline, which is susceptible to backlash. The backlash has a detrimental affect upon the precision of the pressure control, and there is a deterioration in the starting and stopping precision for driving a D.C. motor. Moreover, the D.C. driving motor inevitably produces electric sparks, which may cause an accident particularly when the pressure regulator is used in the atmosphere of an explosive gas, so that there are problems in maintaining safety in the manufacture of semiconductors.